The thermal building insulation don’t works with air leaks in the envelope

In the lower part of a building, by the natural range of pressures, prevail  the air infiltrations that provide cool air (in the winter) and cool the heated inside.

On top predominate the air exfiltration, through which the warm air escapes outside.

This both represents a great energy inefficiency to be considered in any study or audit to achieve effective performance.

It is estimated that nearly half of the energy losses of housing type corresponds to uncontrolled air .


blower_door_1Watch video
We are talking about two concepts: ventilation and airtightness.  Ventilation is the air controlled entry:  if you know this flow , therefore it is possible to know the energy costs involved.  An efficient building must be tightness to have no uncontrolled air intakes. This air volume would be unknown and their energy costs as well.

The blower-door test  measured and locate the air leaks of the building and it allows to know the volume of unwanted infiltrates according to EN 13829. The blower-door method was established in Sweden in 1975 and is fully consolidated in Europe and the U.S. as a basic test of tightness in buildings. It is one of the basics requirements in the Passivehaus standard.

It is based on generating a depression in the building with the normal air intakes sealed  (vents, exhaust fans, …), using a calibrated fan. Measuring airflow and creates a graph relating to the pressure flow, to determine the number of air changes hour due to air infiltration.

blower_door_2On average, a normal household has a air leak area equivalent to a square of 40 cm side, important enough to disrupt any energy calculation. During tjis trest, it is possible to locate these infiltrations with a thermographic inspection,  looking for  cold airflows entering the inside.